RF Characterization, Analysis and Miniaturization Impact of RDL Interconnects

This work aims at providing a RLCG modeling and performance optimization of Redistribution Layer (RDL) in a non-HR substrate up to 67 GHz. Similarly to TSVs, RDL modeling can not be assessed by standard parasitic extraction CAD tools. Therefore, we present complementary measurement and electromagnetic (EM) finite element simulation approaches to provide an accurate modeling over frequency. Firstly, RLCG modeling is developed based on two-port 10 μm and 20 μm width RDL test structures at the back-side of a silicon interposer. All measurements show good agreement with simulations. A Pareto diagram is presented quantifying key process and design parameters for standard RDL technology. Secondly, the impact of the EM configuration is evaluated through several 3D EM scenarios including the role of substrate, TSVs ground and interposer BEOL. Finally, as a way of improvement, miniaturization is proposed with a high density 1 μm RDL on a 10 μm thick substrate.